Polycarbonates are synthetic thermoplastic resins that can, for example, be derived from bisphenols and phosgene, or their derivatives, or by a melt polymerization process. Polycarbonates are a useful class of polymers having many desired properties. They are useful for forming a wide variety of products, such as by molding, extrusion, and thermoforming processes. They are highly regarded for optical clarity, high heat resistance, and enhanced impact strength and ductility at room temperature.
Polycarbonates have seen greater use in applications that require superior optical properties such as high refractive index (RI) and optical clarity, based in part on their cost, design flexibility, and safety profiles. Currently, bisphenol A (“BPA”) based polycarbonates are being used for some optical applications. However, these materials fall short of addressing the current requirements for many optical applications. For example, these BPA-based polycarbonates do not have the requisite heat resistance or refractive index for more demanding optical applications. Moreover, many of the highest index commercial lenses currently available are based on quasi thermoplastic-polyurethane/polyurea based resins.
Therefore, there remains a need in the art for completely thermoplastic polymer compositions, and articles formed from such compositions, having improved dimensional stability, hydrolytic stability and high refractive index.